JP5137537B2 - Robot work motion optimization device - Google Patents

Description

  The present invention relates to a robot work operation optimizing apparatus that achieves the shortest tact time without interfering with the work environment in a work trajectory plan for an industrial robot.

An industrial robot is an industrial device mainly for the purpose of automating various factory operations. In such industrial robot work trajectory planning, it is important not to make work mistakes, to interfere with the work environment, and to achieve the shortest tact time, but it is suitable for offline programming that uses a simulator to plan work. For this reason, it was difficult to completely model the physical shape and operation timing of the work environment, and a compromise was made with an appropriate margin.
In order to improve this, work trajectory planning is done by online programming that had been done before the advent of offline programming, but this needs to be performed by the worker, and results obtained according to the skill of the worker, There was a problem that the work time required to obtain the results varied.

  For example, Patent Document 1 exemplifies a robot controller that improves the accuracy by estimating a robot hand position error using a system model based on a neural network and performing correction. The neural network includes a simulator, A means for learning by using measured values of errors at some predetermined positions as teacher signals is shown.

  Further, for example, in Patent Document 2, there is a means for performing interference check between a laser welding robot and a welding point using a robot simulation apparatus, exemplifying the interfering portion as a programming operator, and supporting adjustment of the moving speed of the robot. It is shown.

JP-A-9-319420 JP 2006-344052 A

  However, in the above conventional technique, an operator needs to select a teacher signal used for learning a system model (a plurality of input / output pairs for the system), but the teacher improves the learning speed and the estimation accuracy. The selection of signals is difficult, and in order to improve the estimation accuracy, it is necessary to prepare a large number of teacher signals, and accordingly, the learning speed tends to become slower. In addition, the operator's intervention is indispensable for the correction of the robot moving speed, and the system model includes a margin that does not match the actual system, so there is a problem in the optimality of the solution.

  The present invention has been made to solve the above-described problems, and in a work trajectory plan of an industrial robot, a robot capable of automatically determining the best work command quickly and with a small number of work trials. The object is to obtain a work motion optimization device.

A robot work operation optimizing device according to the present invention includes a robot unit including a robot and a surrounding work environment of the robot, a robot controller unit that operates the robot unit according to the input work command, and a work command for the robot controller unit. The actual movement of the robot part is input, the operation result of the robot part is observed with respect to those inputs, and the evaluation result of the work result evaluation part for evaluating whether the operation result is appropriate , Improvement work that generates one or more work commands from among a plurality of work command candidates as the next improved work command and generates a work command candidate that is estimated to be the most preferable operation of the robot unit. a command candidate generating unit, based on the work order candidate generated by a modified work order candidate generating unit, against the robot controller And a work instruction unit for outputting the work instruction Te, the improved work order candidate generating unit, having a system model for calculating the interference checking and work operation time of the object of the robot itself and the surrounding work environment, the work directives with a Based on the evaluation value output from the work model evaluation unit and the system model unit that estimates and outputs the predicted value of the evaluation when input, the internal state of the system model unit is updated to a new one, and the prediction of the system model unit The system model reconstruction unit that improves the accuracy and the work command candidate, the degree to which the estimation accuracy of the system model unit becomes more accurate is quantified, and the work command candidate that shows the most preferable value is obtained. A work command candidate optimizing unit that selects one or more and performs an operation to be the next improved work command and outputs the improved work command to the work command unit; It is obtained so as to repeat the processing for outputting the work instruction to the robot controller unit based on improved work command output from the work instruction candidate optimization unit.

The robot work motion optimizing device according to the present invention does not clearly define the shape of the objective function for optimization and estimates the shape of the objective function itself from the result of the trial to operate the robot. The best work command can be automatically determined quickly by the number of trials.

Embodiment 1 FIG.
The illustrated apparatus includes a robot unit 1, a robot controller unit 2, a work result evaluation unit 3, an improved work command candidate generation unit 4, and a work instruction unit 5, and the improved work command candidate generation unit 4 includes a system model unit. 6, a system model reconstruction unit 7 and a work command candidate optimization unit 8 are provided.
The robot unit 1 is an industrial device that includes a robot and a surrounding work environment, and executes various automatic tasks that are targets of the present invention. The robot unit 1 is used, for example, for automating various operations in a factory such as bin picking work for picking up individual parts from piled parts, picking up parts, assembling work, painting work, and welding work.

  The robot controller unit 2 supplies electric energy to a motor or the like attached to the robot in order to realize the work content indicated by the inputted work command by actually moving the robot. The supplied energy is controlled so that the robot moves appropriately. For this purpose, the operation state of the robot is constantly monitored by using a feedback signal from a sensor attached to the robot or a sensor attached to the outside, and a control operation is executed.

The work result evaluation unit 3 receives a work command for the robot controller unit 2 and an actual movement of the robot unit 1 and inputs an evaluation value such as a combination data thereof and a magnitude of an error thereof to an improved work command candidate generation unit. 4 is output.
Based on the data from the work result evaluation unit 3, the improved work command candidate generation unit 4 outputs an improved work command to be next instructed to the robot. That is, the improved work command candidate generating unit 4 generates a work command candidate that is estimated to be the most preferable operation of the robot unit 1 and the operation state of the robot unit 1 due to the generation of the work command candidate. A new work command is generated based on the evaluation result of the work result evaluation unit 3, and an optimized work command is obtained by repeating this.
The work instruction unit 5 is configured to output a work command to the robot controller unit 2 based on the improved work command output from the work instruction unit 5.

  Based on the data from the work result evaluation unit 3, the system model unit 6 in the improved work command candidate generation unit 4 models information such as the robot itself, the shape information of the surrounding environment where the robot is installed, and the operation timing of the peripheral device. Yes. Since it is a model, it is configured to be able to estimate the output for a certain input. For example, when a robot tact time is modeled based on interference check of surrounding environment objects of the robot or a certain work instruction, the estimated tact time is estimated when a work command that does not actually measure the work result is given. Can be output.

  The system model reconfiguration unit 7 updates the internal state (system model) of the system model unit 6 to a new one based on the data from the work result evaluation unit 3. By this operation, the prediction accuracy of the system model unit 6 is improved for a wider range of inputs.

  The work command candidate optimizing unit 8 is configured to use the system model unit 6 to select one or more work candidates to be performed next by the robot and to output the selected work candidates to the work instruction unit 5. As this selection method, for a large number of work command candidates, the work command candidates use the system model unit 6 to quantify the degree to which the estimation accuracy of the system model unit 6 is expected to be more accurate, or The degree to which the time is expected to be shortened is quantified, and one or a plurality of work command candidates whose numerical values indicate the most preferable values are selected. A shorter tact time is preferable, and even a small estimation error is better, so the minimum value is selected. At this time, since there are a plurality of quantified degrees, a method is used in which, for example, several tact times are selected in the order of decreasing values, and then those having a small estimation error are selected. Alternatively, a method is used in which numerical values of two degrees are multiplied, and the result of the multiplication is selected in ascending order.

  The robot work operation optimizing device of the present invention is realized by using a computer, and the robot controller unit 2 to the operation command candidate optimizing unit 8 execute software and software corresponding to each function. It consists of hardware such as CPU and memory.

Next, the operation of the first embodiment will be described.
FIG. 2 is an explanatory diagram showing the operation content related to the candidate selection.
In the model of FIG. 2, a region (current interference identification boundary) f where the robot is estimated to interfere with surrounding objects is drawn. The values on the horizontal and vertical axes indicate work command parameters. The tact time estimation model is represented by F (S _{n + 1} ). S _n is a set of observation results of n times of operations performed n times. F (S _n ) and f (S _n ) represent models that give the most appropriate estimation result from a set of observation results of n operations.

F (S _{n + 1} ) and f (S _{n + 1} ) are estimation models that are updated when the candidate S _{n + 1} to be worked on next is added to the set of observation results. Since it is unclear when interference occurs due to the candidate S _{n + 1} and when interference does not occur, the difference A _fh , the current f (S _n ) resulting from each case is assumed, assuming both cases. A _fg is numerically expressed by the following equation, and a candidate S _{n + 1} that _maximizes the numerical value is finally selected. In FIG. 2, the identification boundary h is a new identification boundary that is observed when interference occurs when the work is performed under a certain condition based on the identification boundary f, and the identification boundary g is It is a new identification boundary that is observed if it does not occur.

を計算しても良い。尚、１００点というのは単なる例であり５０点でも１０００点でも効果は変わらない。また、候補は最終的に一つに絞らなくても、複数選んで、複数を作業結果評価部３で評価しても同等の効果が得られる。 In the above formula, multiplication is used, but F (S _{n + 1} ) is first calculated and about 100 are selected from the smallest ones.

May be calculated. Note that 100 points is merely an example, and the effect does not change at 50 points or 1000 points. Even if the candidates are not finally limited to one, even if a plurality of candidates are selected and evaluated by the work result evaluation unit 3, the same effect can be obtained.

  Although it is a candidate of a work command, for example, it is given as an enumeration of waypoints in the operation of the robot. However, since there are an infinite number of points in space, they are discretized at appropriate intervals. As a result, selectable candidates are a finite set of points, and each candidate is one of them.

F (S _{n + 1} ) and f (S _{n + 1} ) include, for example, multiple regression analysis, support vector machine, support vector regression, kernel regression, Bayes point machine, Bayesian estimation, maximum likelihood estimation, response surface, radius basis A combination of a function model and a parameter determination algorithm such as a function network and a neural network is used.

FIG. 3 is a flowchart showing the operation of the robot work movement optimizing apparatus shown in FIG.
First, in step ST11, the robot unit 1 performs an initial operation experiment under several work command conditions. Next, in step ST12, the system model reconfiguration unit 7 determines the interference identification boundary of the system model unit 6 from the operation result obtained at that time (operation result for each of a plurality of experimental points). Next, in step ST13, the work command candidate optimization unit 8 sets a point in the vicinity of the identification boundary determined in step ST12 as the next experimental candidate point. Then, it is determined whether or not all candidate points have already been experimented (step ST14). If so, the process ends. If not, the process proceeds to step ST15. In step ST15, the system model unit 6 calculates the above formula (1) or formula (2) for all generated candidate points. Next, in step ST16, the work command candidate optimization unit 8 selects a candidate point at which this value is maximized as the next experimental point. Next, in step ST17, an operation experiment is actually performed using the experimental point selected in step ST16, and an operation result is obtained. And it returns to step ST12 and repeats these processes below.

By the way, the large value of the sum of A _fh and A _fg calculated in this embodiment / (difference between A _fh and A _fg +1.0) means that interference occurs as a result of the work by the candidate points. This means that the amount of change in the identification boundary is substantially the same when the interference occurs and when no interference occurs, and the amount of change is large. That is, the difference value (denominator) becomes smaller if the amount of change becomes equal, and the sum value (numerator) becomes larger if the amount of change is large. From these points, as the candidate of the next experimental point, it is possible to select a point that is likely to be predicted that the identification boundary will correctly pass therethrough.

  In the above embodiment, the value of 1.0 in the sum / (difference + 1.0) is avoided in order to prevent the sum / difference value from becoming infinite when the difference is 0. It may be a numerical value other than 1.0. However, if the value is decreased, the effect of the difference is greatly evaluated, and if the value is increased, the effect of the difference is evaluated small. Therefore, a value is appropriately selected according to conditions and the like.

Also, when constructing the system model unit 6 first, it is necessary to make the S _n. This is an experiment using an orthogonal table. Not only L8 but also L4, L16, L32, L64, L9, L27, L81, L243, L12, L18, L36, L72, etc. may be used, or multi-way layout, Latin square, Greco Latin square, A uniform plan, an optimum plan such as D-optimum, G-optimum, and A-optimal, a composite plan in response surface plan, a Box and Behnken plan, or a completely random plan may be used as appropriate. Alternatively, select the work order to consider the operator experience to a promising, it may have been made a S _n.

  When the next work command candidate is generated, it is checked whether the previous experimental points are uniformly distributed. If not, the candidate points that have not been tested yet are found. The experiment may be performed by randomly selecting one of the points. For example, whether or not the experimental points so far are uniformly distributed in the space where the experiment can be performed is tested by the chi-square test. If the test points are unevenly distributed as a result of the test, one of the lattice points not yet tested is selected at random. In this case, in order to search the searchable space evenly, even if the correct interference identification boundary is scattered like a small island, the speed at which the identification boundary converges to the correct position should be increased. There is an expected effect.

When using a support vector machine as a model, several parameters of the support vector machine can be adjusted. Simply put, the expressive power of the identification boundary can be adjusted. For example, when it is desired to draw a complicated identification boundary, a certain parameter value may be increased. However, as a disadvantage, the time required to process the support vector machine formula increases. If the value of the parameter is reduced, the calculation time is shortened, but it may not be possible to create an identification boundary that can correctly identify the results of all experimental points.
Therefore, the value of the corresponding parameter is initially made small to reduce the calculation time. And in the step of determining the identification boundary, the value of the corresponding parameter can be completely separated when it becomes impossible to obtain the identification boundary that completely separates the result of the experimental points obtained up to that point. Configure to increase until At the same time, it is configured to reduce until just before it can not be completely separated. Accordingly, there is an effect that it is possible to obtain a robot work motion optimization device that requires a short calculation time for selecting an experimental point candidate.

As described above, according to the robot operation optimization device of the first embodiment, the robot unit including the robot and the surrounding work environment of the robot, the robot controller unit that operates the robot unit according to the input operation command, , The work command to the robot controller unit and the actual movement of the robot unit as input, the operation result of the robot unit with respect to those inputs is observed, the work result evaluation unit to evaluate whether the operation result is appropriate, An operation in which the evaluation value of the operation result evaluation unit is input, and one or more operation commands are selected from the plurality of operation command candidates as the next improved operation command, and the operation of the robot unit is estimated to be the most preferable. an improved work order candidate generating unit for generating a candidate command, based on the work order candidate generated by a modified work order candidate generating unit, robot And a work instruction section for outputting an operation command to the controller unit, improved work order candidate generating unit has a system model for calculating the interference checking and work operation time of the object of the robot itself and the surrounding work environment, Based on the system model part that estimates and outputs the predicted value of evaluation when a certain work command is input, and the evaluation value output from the work result evaluation part, the internal state of the system model part is updated to a new one. The system model reconstruction unit that improves the prediction accuracy of the model part and the degree to which the estimation accuracy of the system model part becomes more accurate for the work command candidate are quantified, and the obtained numerical value shows the most preferable value A work command candidate optimizing unit that selects one or a plurality of work command candidates, performs an operation to be the next improved work command, and outputs the improved work command to the work instruction unit; Provided, the work instruction unit, By repeating the processing for outputting the work instruction to the robot controller unit based on the output improved work order from the work instruction candidate optimization unit, since to obtain the work order optimized Therefore, the best work command can be automatically determined quickly with a small number of work trials.

Contact name operation of the robot is carried out in a so-called robot simulator, be configured to perform an interference check by performing an interference check operation between the environment model and the robot model built in the simulator, the actual robot Attach a distance sensor to each hand or arm, or use joint torque sensor or joint torque estimation calculation to detect and interfere with contact between the environment and the robot when the actual robot is operating in the actual environment. Even if it is configured to check, the same effect can be obtained.

  Furthermore, while the above has been described with respect to an example where the robot avoids interference with obstacles, other forms may be employed. In a system in which a robot and a vision sensor are combined, when a vision sensor installed in a fixed manner captures an object, the robot needs to move to a position where the body of the robot does not enter the field of vision of the vision sensor. In other words, the robot needs to move out of the field of view of the vision sensor and be on standby so as not to interfere with the imaging of the vision sensor. When the imaging of the grasped object by the vision sensor is completed, the robot moves again within the field of view of the vision sensor and performs a grasping operation in order to grasp the work object. At this time, it is considered that it is advantageous for shortening the entire working time that the robot is waiting outside the visual field of the vision sensor. That is, it is possible to operate in a short tact time while avoiding the interference of the vision sensor by processing, assuming that it is the same judgment as the interference check described above whether it is in the vision sensor field of view or not. There is an effect that an orbit is obtained.

Embodiment 2. FIG.
Since the configuration of the second embodiment on the drawing is the same as that of the first embodiment, FIG.
A robot work command is usually described in a kind of programming language called a robot language. The grammar often follows that of the BASIC language. Robot work is assigned to each line of those languages. Information other than the robot operation such as numerical calculation is also described, but here, only the description regarding the robot operation and the command regarding the communication with the peripheral device are focused.

In the present embodiment, each time the robot unit 1 performs work, the work result evaluation unit 3 records the number of times of execution and the time required for execution of each work. This recording is performed with the actual robot operating in the actual environment. Based on the record, the improvement work command candidate generation unit 4 calculates and calculates the product value of the time required for execution × the number of executions, and arranges them in descending order.
Note that this ranking can be presented to the operator and is out of the viewpoint of automatic optimization. However, it is better to replace the work at the top of the ranking from robot work to dedicated tool work or dedicated processing equipment. You can also consider whether.

  In the present embodiment, the improvement work command candidate generation unit 4 is based on information on the execution time of each operation procedure observed by the work result evaluation unit 3. As long as there is no hindrance to work execution, the operation procedure is changed so as to reduce the tact time in the entire operation, and a work command is generated. Specifically, it is sequentially determined whether or not the following items are applicable, and when they are applicable, the work operation is actually improved.

(1) Optimization of operation with high execution frequency Using the method described in the first embodiment, work operation with high execution frequency is improved toward higher-speed operation. This corresponds to, for example, realizing an operation that passes through an obstacle.

(2) Optimization of compound branch For example, in the situation where the work arrival waiting position from the upstream process is programmed and the actual position arriving from the upstream process varies, it is statistically Probability distribution of arrival positions is obtained. The workpiece arrival waiting position is moved to the center of this distribution.
Alternatively, when there are a plurality of types of workpieces that arrive and the hands that can handle them are different, it is necessary to change the hands. As the work operations are repeated, the probability distribution of the actual arrival type and the conditional probability regarding the arrival order are obtained statistically. According to this distribution, the robot program is rewritten so that the hand is attached in advance.

(3) Optimization of conditional branch decision processing It may take some time to judge the situation, such as inspection after machining. The probability is statistically determined whether the observed branching probability is true or false. In accordance with this probability, the operation is switched to an inspection operation that can be quickly determined. Alternatively, when there are a plurality of inspection processes, an inspection sequence with a high probability of a comprehensive final determination result is generated, and a work operation for realizing this is reprogrammed.

(4) Execution order exchange Based on the observed work result information, the execution order is exchanged in order that finishes earlier. The order is changed so that the work that can be done first is completed during the work completion waiting time from the peripheral device. Whether it is meaningful to exchange can be judged from each observed work time.

(5) Work in-line The work that needs to be changed can be done in advance by placing multiple workpieces in the buffer area with the same hand in advance, and assembling and reusing jigs that are used many times. Rewrite the robot program.

(6) Resource allocation optimization Optimization of temporary table use, optimization of finger assignment when using double hands, and optimization of dedicated machine processes such as pressing.

The improved work command candidate generation unit 4 outputs the result of performing the above items to the work instruction unit 5 as an improved work command. A work command is output from the work instruction unit 5 to the robot controller unit 2, and the robot unit 1 operates.
Although it is an end condition for repetition, when the tact time is not updated for a long time, when the magnitudes of A _fh and A _fg become smaller than a predetermined value in the operation in the work command candidate optimization unit 8 I will end it.

  As described above, according to the robot work motion optimizing device of the second embodiment, the improved work command candidate generation unit creates a work command by enumerating a series of motion procedures in the robot programming language, Based on the information on the execution time of each operation procedure observed by the result evaluation unit, unless there is a hindrance to work execution, the operation procedure is changed so as to shorten the tact time in the entire operation so that a work command is generated. As a result, there is an effect of obtaining a robot work motion improvement device capable of automatically determining the best work command quickly and with a small number of work trials.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the robot operation | movement optimization apparatus by Embodiment 1 of this invention. It is explanatory drawing which shows the operation | movement of the interference identification boundary and candidate selection of the robot operation | movement optimization apparatus by Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the robot operation | movement optimization apparatus by Embodiment 1 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Robot part, 2 Robot controller part, 3 Work result evaluation part, 4 Improvement work command candidate generation part, 5 Work instruction part, 6 System model part, 7 System model reconstruction part, 8 Work command candidate optimization part.

Claims (3)

A robot section composed of a robot and a surrounding work environment of the robot;
A robot controller for operating the robot in accordance with the input work command;
Work result evaluation for accepting an operation command to the robot controller unit and an actual movement of the robot unit as input , observing the operation result of the robot unit with respect to those inputs, and evaluating whether the operation result is appropriate And
The evaluation value of the work result evaluation unit is input, and one or more work commands are selected as the next improved work command from among a plurality of work command candidates, and it is estimated that the operation of the robot unit is most preferable. An improved work command candidate generating unit for generating work command candidates,
The improved working on the basis of a command candidates the work order candidate which is generated by the generation unit, and a work instruction section for outputting an operation command to the robot controller,
The improved work command candidate generator is
A system model unit that performs an interference check between the robot itself and an object in the surrounding work environment and calculates a work operation time, and a system model unit that estimates and outputs a predicted value of an evaluation when a certain work command is input;
Based on the evaluation value output from the work result evaluation unit, the system model reconfiguration unit that updates the internal state of the system model unit to a new one and improves the prediction accuracy of the system model unit,
For the work command candidate, the degree to which the estimation accuracy of the system model part becomes more accurate is quantified, and one or more work command candidates whose obtained numerical values indicate the most preferable values are selected, and the following A work command candidate optimizing unit that performs an operation as an improved work command and outputs the improved work command to the work instruction unit;
The work operation optimizing device for a robot, wherein the work instruction unit repeats a process of outputting a work command to the robot controller unit based on the improved work command output from the work command candidate optimization unit. The work command candidate optimization unit, as the degree to which the estimation accuracy of the system model unit becomes more accurate,
When the obtained work motion interferes with a surrounding object, the interference identification boundary f is obtained when it does not interfere, and when the work motion is performed with a certain work command candidate based on the identification boundary f, no interference occurs. A new identification boundary g when the result is assumed to be observed, and a new identification boundary h when the result of the interference is assumed to be observed are obtained, and a region sandwiched between the identification boundary h and the interference identification boundary f is obtained. 2. The robot work motion optimizing device according to claim 1, wherein a calculated value of the sum of the regions sandwiched between the identification boundary g and the interference identification boundary f / (difference + numerical value) is used . The work result evaluation unit receives a work command for the robot controller unit and an actual movement of the robot unit, and inputs the combination data and the evaluation value thereof for n times (n is an integer of 2 or more). it outputs a set S _n of the evaluation value,
The improvement work command candidate generator is
The work from the set S _n of the evaluation value output from the result evaluation unit, and updated to the new internal state of the system model unit by using a predetermined parameter determination algorithm, improve the prediction accuracy of the system model unit A system model reconfiguration unit
As a system model for estimating an evaluation when a certain work command is input, a tact time estimation model F (S _n ), and an identification boundary estimation model f (an area where the robot interferes with surrounding objects) S _n ), and the estimated model F (S _n ) and the estimated model f (S _n ) are a system model part that is a function model including the parameter determination algorithm;
In the improved work order candidate generating unit, then in obtaining improved work order to be output to the robot, from a plurality of work order candidate, when only one in addition to S _n making S _{n + 1,} the work in the case of observation by the command candidates are tentatively assumed robot and the peripheral object interferes, make S _{n + 1} assuming that no interference respectively, with the respective S _{n + 1,} the system model by the system model reconstruction unit Update the identification boundary f (S _{n + 1} ) obtained in each case as the identification boundary h and the identification boundary g, and obtain the estimated model F (S _{n + 1} ), and then identify the identification boundary h and the identification boundary g. The difference in area from the identification boundary f is A _fh and A _fg , and the following equation (1)

And a work command candidate optimizing unit that performs an operation to set the work command candidate having the largest calculated number as the next improved work command and outputs the improved work command to the work instruction unit. 2. The robot work motion optimizing device according to claim 1, wherein

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